Ah, don't be upset, that's what the forums are for. Ask, and you'll get an answer pretty fast.
The UpdateNormals command just automatically recomputes the normals of your mesh. This is handy by example if you do things like mesh generation (you create a mesh on the fly) and don't want to bother recomputing the normals by yourself (that is, you build the mesh, and then just do a UpdateNormals). If you just load meshes from files (.x, .3ds, .b3d), there is very few good reasons why you would want to do an UpdateNormals.
EDIT: Cross post. See? The answers were so fast to come taht I've been beaten :)
The UpdateNormals command just automatically recomputes the normals of your mesh. This is handy by example if you do things like mesh generation (you create a mesh on the fly) and don't want to bother recomputing the normals by yourself (that is, you build the mesh, and then just do a UpdateNormals). If you just load meshes from files (.x, .3ds, .b3d), there is very few good reasons why you would want to do an UpdateNormals.
EDIT: Cross post. See? The answers were so fast to come taht I've been beaten :)